| Popis: |
We examined the expression of MHC class I and II in the arterial endothelium of interferon-γ (IFN-γ, GKO) and IFN-γ-R (IFN-γ-R, GRKO) gene knockout mice in comparison with mice with intact IFN-γ and IFN-γ-R genes, BALB/c and 129Sv/J wild-type, respectively. The GKO and GRKO were produced by gene targeting. MHC class I and II expression was assessed by mAb binding to frozen tissue (kidney, spleen, heart, liver) sections by immunoperoxidase staining in the basal state and after various stimuli: allogeneic cells, oxazolone skin sensitization, LPS, and rIFN-γ. As controls, we also examined the expression of two other IFN-γ inducible genes present in the endothelium, Ly-6 and ICAM-1. We found that basal class I expression was present in the small arteries and arterioles of BALB/c and 129Sv/J wild-type mice but absent from arterial endothelium of GKO and GRKO mice. Class I was induced in the endothelium of BALB/c and 129Sv/J wild-type mice by three in vivo stimuli: allogeneic, LPS, and oxazolone, whereas class II was only induced after allogeneic stimulus. Administration of rIFN-γ induced class I in the endothelium of GKO and BALB/c wild-type mice. The basal expression of Ly-6 and ICAM-1 was similar in the arteries of GKO and BALB/c wild-type mice, indicating that, the basal expression of these proteins in endothelium is IFN-γ independent, unlike class I. In summary, basal class I expression in arterial endothelium is not constitutive as previously believed, but is dependent on basal IFN-γ production. IFN-γ has an essential role in the induction of class I and II expression in arterial endothelium. The fact that MHC class I is induced in endothelium may be useful therapeutically for reduction of immune recognition in transplantation. |
